The invention describes a method to thin the surface of a material and, more particularly, to a method to thin the surface of a material utilizing an article with a discontinuous, moveable surface.
Thinning of surfaces to thicknesses of several microns or several tens or hundreds of microns is often required for purposes including microscopy analysis and manufacturing of parts made from materials including silicon and glass. Various techniques can be used to thin surfaces, both mechanical and non-mechanical. For example, in integrated packages, such as plastic encapsulated devices, thinning can be achieved by a planar lapping technique using diamond slurries. Etching compounds and reagents can be used on some materials to effect thinning. Ion milling can be used by applying a focused ion beam to erode semiconductor materials. Mechanical means such as lapping and dimpling can be utilized for a variety of materials.
Dimpling is a technique that was developed for the preparation of materials for microscopy, particularly transmission electron microscopy (TEM), analysis. For many materials the preparation sequence often involves disc cutting, planarizing, dimpling, and ion-milling. Dimpling produces a disc, commonly 2.3 or 3.0 mm in diameter, with a thinned central area and a thicker outer rim, thus forming a bowl-shaped cut known as a dimple. This geometry is achieved by the action of a rotating wheel carrying an abrasive slurry to erode a specimen simultaneously rotating about a perpendicular axis.
The technique is time-consuming as the low RPM tool speed can take hours to days to grind and polish surfaces made from materials including ceramics, semiconductors, metal oxides, and soft and hard metals. Such mechanical thinning can also produce stress in the material such that some materials, particularly hard and brittle materials, can fracture before the desired material thickness is achieved.